In the prior art there has been developed a wide variety of systems for producing useful work. Some of the systems, such as nuclear fission, suffered from bad publicity. Others such as conversion of energy content of substances such as wood, coal, and petroleum, are suffering from scarcity of the fuel and from pollution by the waste products of combustion. Consequently, there is increasing emphasis on the use of solar energy and similar readily available fuels that do not contaminate. The systems for using solar energy are referred to as solar systems. These systems have taken a wide variety of forms ranging from the photovoltaic cell systems that convert the radiant energy directly into electrical energy, to the more mundane systems that convert the energy to heat for heating of fluid for use in generation of power.
The photovoltaic systems have been relegated to fairly exotic uses heretofore because of the cost. Regardless of which system is employed, it is generally conceded to be beneficial to employ a concentrating principle in which the sun's radiant energy from a much larger area than the collector, per se, is directed, or focused, onto the collector that uses the radiant energy.
In a typical installation heretofore, the collector was mounted on an expensive tower or the like that held the collector high for directing the energy onto it; and many reflectors were spaced about the central collector and used sensors for directing the radiant energy onto the collector.
In a patent by co-workers Floyd Blake and Lynn Northrup, Jr. and assigned to the assignee of this invention, entitled "Solar System Having Improved Heliostat and Sensor Mountings", U.S. Pat. No. 4,227,513, the descriptive matter of which is incorporated herein by reference for details that are omitted therefrom, there was disclosed an improvement that eliminated the prior major expense of having to have the reflectors mounted on one post and the sensors mounted on another post, both of the posts being deeply embedded in the earth's surface such that they were firmly anchored and resisted receiving minor surface movements that were independent of each other. In that patent application there was disclosed an improved co-mounted reflector and sensor on a single post to eliminate that nonfunctional and inefficient expense.
Despite that improvement, it has been found functionally, flexibly, and economically advantageous to eliminate the sensor, per se; and to control the heliostat by a computer that calculates a commanded position to which the heliostat is moved in azimuth and elevation for a given time of the day.
From the foregoing, it can be seen that the prior art did not solve the problem of providing the most economical, most accurate, and most flexible way of controlling heliostats to reflect solar energy onto a collector when multiple heliostats were employed in an array of many heliostats about a collector (such that many sensors and control circuits would be required.)